One of the Commissioner's most visible roles is in the employment, supervision and dismissal of senior executives in individual Government departments; by preventing Ministers of the Crown from becoming personally involved in employment decisions, this acts as a safeguard against politicisation of the public service.

The Commissioner has a statutory duty to act independently of Ministerial direction, except in matters concerning the appointment and dismissal of Departmental chief executives.

Section 3 of the Act specifies that the Commissioner is to be appointed by the Governor-General in Council on the recommendation of the Prime Minister.

Section 17 of the Act lists a small number of circumstances in which the Commissioner is deemed to have resigned.

The Governor-General may suspend the Commissioner under Section 16 for misbehaviour or incompetence, but must then explain why to the House of Representatives within seven sitting days; and even then the Commissioner is safe in his position unless the House resolves within three weeks after receiving the Governor-General's explanation to remove him or her from office.

At the end of the first decade of the twentieth century, New Zealand's public sector was widely considered to be inefficient and wasteful.

The Act and the new Commissioner removed Ministers' direct involvement in appointments and personnel administration, separating the 'political' and 'administrative' functions, both in conduct of the Government's business and in management of the Public Service itself.